Use Of Aspheric Surfaces Research Articles

Improved Analytical Theory of Ophthalmic Lens Design

A revisited form of the classic third-order ophthalmic lens design theory that provides a more precise and meaningful use of aspheric surfaces and a generalization of the standard oblique errors is presented. The classical third-order theory follows from the application of the Coddington equations to a ray trace through the lens and the expansion of the incidence angles and the surface sagittas appearing on them up to order two of the radial coordinate. In this work we show that the approximations for surface sagittas and angles can be decoupled, and the lens oblique powers predicted by the proposed theory provides a better fit to the numerical results obtained by exact raytracing and multi-parametric optimization than the classical third-order theory does. Modern ophthalmic lens design uses numerical optimization and exact ray tracing, but the methods presented in this paper provide a deeper understanding of the problem and its limitations. This knowledge and the more general merit functions that are also presented may help guide the numerical approaches.

制冷型中波红外偏振成像光学系统设计

In addition to the advantages of traditional infrared intensity imaging, such as long detection distance, all-weather working and good concealment, infrared polarization imaging technology based on the difference between the target and background polarization characteristics can effectively reduce background interference, suppress background clutter, enhance image contrast, improve signal-to-noise ratio, and has broad application prospects. In order to effectively suppress the background clutter interference in the process of air and sea detection, enhance the target detection ability in fog, haze and smoke, as well as the backgrounds of small temperature differences and low illumination, the design of a four channel aperture sharing medium-wave infrared polarization imaging optical system with a focal length of 240 mm was completed. Tolerance analysis was carried out by using Monte Carlo method to ensure the rationality of the precision of optical system processing and assembly. The results of image quality analysis show that the MTF of the optical system is close to the diffraction limit, aberrations have been effectively corrected, and the imaging quality is good. The influence of Narcissus effect on the imaging quality of the cooled infrared optical system was verified by Narcissus analysis. In addition, the optical system proposed has a compact structure and high transmittance, avoiding the use of aspheric surfaces, and has good processing and assembly technique.

Design Technology of New Four-Element Zoom Optics with a Comperhensive Use of Aspherical Surfaces

Design Technology of New Four-Element Zoom Optics with a Comperhensive Use of Aspherical Surfaces

Use Of Aspheric Surfaces In Infrared Optical Designs

The cost effectiveness of using aspheric surfaces in infrared systems is reviewed. In particular, two design studies are described, the first of a Maksutov-type objective and the second of a high numerical aperture pyroelectric vidicon objective. In the first case, the use of first one and then two aspheric surfaces results in an increasing ability to satisfy all of the aberration and dimension requirements of its specification. In addition, a size versus raw material trade-off becomes possible. In the second case, a four-element spherical design is compared with a two-element aspheric design over a large range of numerical apertures. The analysis demonstrates that the improved transmission and reduced materials costs that result from the use of aspheric surfaces outweigh the cost of aspheric manufacture. The paper concludes that in the cases examined, aspherics are highly cost effective, provided that a facility for diamond machining to an optical finish, without subsequent polishing, is available.

Best-fit spheres and conics as an aid in the manufacture and testing of diamond-turned aspheric optics

Abstract The development of high-quality and high-accuracy diamond turning has led to an increase in the use of aspheric surfaces in optical systems, especially those operating in the infrared. In the interests of economy it is important to start from a ‘best-fit’ spherical surface, which can be produced by cheaper conventional methods. The testing of these aspheric surfaces also poses a problem, which can often be partially solved by considering the departure of the aspheric from a best-fit conic rather than the more usual sphere. This paper looks at the computation of these best-fit spheres and conies.

Best-fit Spheres and Conics as an Aid in the Manufacture and Testing of Diamond-turned Aspheric Optics

Abstract The development of high-quality and high-accuracy diamond turning has led to an increase in the use of aspheric surfaces in optical systems, especially those operating in the infrared. In the interests of economy it is important to start from a ‘best-fit’ spherical surface, which can be produced by cheaper conventional methods. The testing of these aspheric surfaces also poses a problem, which can often be partially solved by considering the departure of the aspheric from a best-fit conic rather than the more usual sphere. This paper looks at the computation of these best-fit spheres and conies.

Effects of Aspheric Surfaces on Optical Performance and Their Application to Lenses for 35mm Cinematography

The practical use of aspheric surfaces in optical devices, such as parabolic mirrors or illuminating condensers, is well-known. Technical problems in the design and manufacture of such surfaces had to be overcome before the incorporation of aspheric surfaces into the construction of high precision optics, such as camera lenses for motion pictures and television, could be attempted. An overview of the performance of aspheric surfaces is given, and their limitations are mentioned. Spherical aberration, distortion, and astigmatism can be controlled by their use. The introduction of an aspheric surface into the design of a lens produces two types of effects: direct effects permit controlling of a specific aberration, and indirect or secondary effects may allow for the simultaneous control of another aberration. Greater lens compactness and reduction of the number of required lens elements may result. Three fundamental parameters for the measurement and evaluation of an aspheric surface are explained. A short description of various possible grinding and polishing methods is given. The accuracy of the surfaces obtained can be measured by the use of interference fringes or by means of a feeler in combination with a laser. Canon designed their first aspheric lens in 1971. It is shown that the aspheric design reduces aberration fringes, gives greater freedom from flare, and improves contrast. A series of four aspheric high speed lenses for motion-picture use was created. Some details of their design and contruction, including the “floating” focusing mechanism, are mentioned. A Class III Scientific or Technical Award from the Academy of Motion Picture Arts and Sciences resulted from this technological achievement.

The Correction of Optical Systems

The author has on previous occasions analyzed the optical image as a superposition of five images corresponding to image formation of first order (astigmatism), second order (asymmetry), third order (Gullstrand errors), fourth order (secondary coma), and fifth order (secondary spherical aberration). To a set of concentric circles in the exit pupil corresponds a set of concentric similar figures in the image, the dimensions of which vary with the first, third, and fifth powers of the aperture, and to a set of eccentric similar figures, the dimensions of which vary with the second and fourth powers of the aperture. The vector sum of all five figures gives the spot diagram and with it the light distribution in the image. Since the elementary images are of simple forms, the change of system data can be easily used to balance the image. Recently the use of aspheric surfaces has become rather common, so we shall also demonstrate how to correct an optical system by the proper selection of the coefficients of an aspheric surface.

Use of aspherical surfaces in the design of magnifiers for binocular vision.

IN a recent communication1, Coulman and Petrie propose that low-power aspherical magnifiers should be designed for coincidence of the two monocular fields of vision rather than for absence of distortion, and suggest that this has not hitherto been done.

Use of Aspherical Surfaces in the Design of Magnifiers for Binocular Vision

DURING recent years, renewed and increasing interest has been shown in the use of aspherical surfaces as a means of improving the performance of optical instruments, and one notable application has been to low-power singlet lenses for industrial inspestion purposes. Nevertheless, to the best of our knowledge, no serious attempt has hitherto been made to correct these lenses for binocular vision, and as a result of extensive experiments in this connexion it is now clear that a major contribution to the comfort of the user of such lenses over prolonged periods can be made by designing primarily for binocular viewing. It is proposed to publish a more detailed account of this investigation elsewhere; but in the meantime some notes on the more important features of the design may be of interest.